Ballistic articles such as bulletproof vests, helmets, structural members of helicopters and other military equipment, vehicle panels, briefcases, raincoats and umbrellas containing high strength fibers are known. Fibers conventionally used include aramid fibers such as poly(phenylenediamine terephthalamide), graphite fibers, nylon fibers, ceramic fibers, glass fibers and the like. For many applications, such as vests or parts of vests, the fibers are used in a woven or knitted fabric. Fibers may be encapsulated or embedded in a matrix material.
Phenolic or modified polyester can also be added to these high strain ballistic fabrics in order to form composites in which the resin does little more than keep out water. Often a nonbonding rubber latex is added to enhance nonbonding to the high strain, high tenacity fiber (such as Kevlar®), in order that the high strain fiber breaks free of the composite matrix under impact and goes into tension along its length, immediately and thus carrying the impact load over as large an area as possible. The stopping power of the ballistic fabric stack is thereby increased.
Ionomers have been used to form composites with ballistic fibers. In U.S. Pat. No. 4,879,165 is disclosed an armor structure or high impact structure comprising a plurality of zones, at least one zone comprising an extruded ionomer resin. For example one ionomer or ionomer resin of the '165 invention is obtained by combining a copolymer of ethylene-methacrylic acid or ethylene-acrylic acid and a polyamine which contains at least one R—CH2—NH2 group, and the R may contain: (—CH2NH2)x; (—NH2)x; or (R′R″NH)y, where x=1 or more, and y=0 or more. R′ and R″ may be any organic groups.
The present inventors have discovered compositions that show a significant improvement in ballistic performance over the existing art in this area.